We are IntechOpen, the world’s leading publisher of Open Access books Built by scientists, for scientists 4,500 118,000 130M Open access books available International authors and editors Downloads Our authors are among the 154 TOP 1% 12.2% Countries delivered to most cited scientists Contributors from top 500 universities Selection of our books indexed in the Book Citation Index in Web of Science™ Core Collection (BKCI) Interested in publishing with us? Contact [email protected] Numbers displayed above are based on latest data collected. For more information visit www.intechopen.com Chapter 2 Cytogenetic Relationships of Turkish Oaks AykutAykut Yılmaz Yılmaz Additional information is available at the end of the chapter http://dx.doi.org/10.5772/intechopen.78265 Abstract The genus Quercus L. represented by 18 species belonging to three sections (Quercus L., Ilex Loudon and Cerris Loudon) in Turkey has a problematic taxonomy especially because of widespread hybridization observed frequently among oak species. In the present chapter, detailed karyotypic investigation of the 16 oak species from three sections in Turkey, their taxonomic relationships with each other and European oaks and finally situations that increase the variation and taxonomic problems among oak species in Turkey were evalu- ated to contribute to the taxonomic relationships of the genus. The somatic chromosome number in all taxa examined confirmed that the chromosome number of the genus is con- sistent with 2n = 24. However, some differences were determined among species, although similar results were observed in many oak species in Turkey contrary to European oaks. Keywords: Quercus, Ilex, Cerris, Turkey 1. Introduction The genus Quercus L. belonging to the Fagaceae family is one of the most abundant and eco- nomically important genera of woody plants in temperate and tropical areas of the northern hemisphere. The genus contains over 500 species and is distributed across the North and Central America, Asia, Europe and North Africa [1]. Turkey has a large land area covered by forest with 21.2 million ha. The oaks in Turkey are ecologically and economically very important trees and make up 26% of the total forest area. However, a large part of this is not so productive due to especially excessive cutting and graz- ing. Turkey is one of the richest countries in species number, diversity and endemic species [2]. The genus is currently represented by 23 taxa and 3 endemic species such as Q. aucheri, Q. vulcanica and Q. macranthera subsp. syspirensis [2, 3]. © 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. distribution, and reproduction in any medium, provided the original work is properly cited. 20 Cytogenetics - Past, Present and Further Perspectives The most important reason which influences species number and diversity is the loca- tion and geomorphological structure of Turkey [4]. Turkey is composed of Anatolian and Thrace peninsulas where three phytogeographic regions are crossed such as Irano-Turanian, Mediterranean and Euro-Siberian regions. Its geomorphological structure reveals numer- ous climatic regions which influence the flora. The main climatic changes in Turkey occured especially at the beginning of the Holocene, and these climatic conditions have affected the topography and distribution of today’s plant vegetation [5]. Today’s plant zones occured in Anatolia, about 8000 years ago [5–11]. During the last glacial period, coastal plants, such as Pinus sylvestris and Picea sp., which were grown in cold climate in East Black Sea, have been taken up to higher places up gradually, and their places have been occupied by broad-leaved forests, such as Quercus spp., Fagus, and so on, living in the shaded coastal areas [5]. Another important factor affecting species diversity and distribution is the location of Turkey between the Asian and European continents. As a result, Anatolia has served as a migration route and refuge regions for many plants and animals from Asia into Southeast Europe [12]. Besides its location and phytogeographical regions, Anatolian Diagonal which divides Anatolia as eastern and western parts is another factor affecting species diversity, number and distribution [4, 12–15]. Anatolian Diagonal separates many plant and animal species into eastern and western Anatolia. Turkey is a rich country in the aspect of oak variation with 18 species belonging to three sec- tions (Quercus L., Ilex Loudon, and Cerris Loudon). Section Quercus L. is characterized by the greatest number of species among the three sections in Turkey: Q. pontica C. Koch., Q. robur L., Q. hartwissiana Steven., Q. macranthera subsp. syspi- rensis (C. Koch.) Menitsky, Q. frainetto Ten., Q. petraea (Mattuschka) Lieb.,Q. vulcanica (Boiss. Heldr. ex) Kotschy, Q. infectoria Oliver, Q. pubescens Willd and Q. virgiliana Ten. [2]. Section Ilex Loudon is characterized by the evergreen trees and shrubs: Q. ilex L., Q. coccifera L. and Q. aucheri Jaub. et Spach. [2]. Section Cerris Loudon is the second largest section and includes five species;Q. libani Olivier, Q. trojana Webb, Q. cerris L., Q. brantii Lindl. and Q. ithaburensis subsp. macrolepis (Kotschy) Hedge et Yalt. [2]. Vegetative characters are preferred instead of reproductive characters in situations which are not helpful in the classification16 []. Leaves are good indicators of putative hybridization and very useful for identification of oaks. Individuals that exhibit intermediate morphologi- cal characters can be seen widely because of interspecific hybridization and even sometimes exhibit high morphological variation, and it is not possible to identify an oak tree to a species. In this case, acorns are secondary important materials in the seperation of oak species [17–19]. Although vegetative characters are crucial to differentiating species within the genus and are freguently prefered in the identification of oaks, these are insufficient and risky because of hybridization behaviors caused by weak reproductive barriers between oak species. Oaks are wind-pollinated species and they can spread across wide geographic regions [20–22]. As a result, many oak species grow in mixed populations that increase the hybridization in the same or different sections. In addition to wind-pollination and weak reproductive barriers Cytogenetic Relationships of Turkish Oaks 21 http://dx.doi.org/10.5772/intechopen.78265 between species [14, 22–25], insufficient diagnostic morphological characters [24–25] and the lack of investigations for each taxon such as ecological, historical and genetic descriptors [25] make problematic the genus Quercus in Turkey and similarly in the world. Scientific interest has recently moved from classification of the species with classic descriptors to understanding of oak evolution with molecular markers [24–27]. However, oak taxonomy is still problematic and under debate. Although cytologic studies are very important and useful for determinig taxonomy and polyploidy, studies on the genus Quercus are still insuf- ficient because of the small size of chromosomes and difficulties in the germination of acorns. 2. Materials and methods for karyotype analyses of Turkish oaks In our previous studies, acorns belonging to 16 oak species from three different sections were collected in different times from various locations in Turkey. The species, sections and loca- tions are presented in Table 1. Acorns of three species (Q. libani, Q. petraea subsp. iberica and Q. infectoria subsp. infectoria) were germinated in plastic cups filled with water in room tempera - ture [28]. The other 14 Quercus taxa studied (Q. robur, Q. hartwissiana, Q. macranthera subsp. syspirensis, Q. frainetto, Q. vulcanica, Q. infectoria subsp. boissieri, Q. pubescens, Q. virgiliana, Species Section Locations Q. coccifera Ilex Uşak, Hatay Q. ilex Ilex Zonguldak, Düzce Q. aucheri Ilex Aydın, İzmir, Muğla Q. cerris Cerris Balıkesir Q. ithaburensis Cerris Çanakkale, Balıkesir Q. libani Cerris Between Erzincan-Tercan Q. trojana Cerris Uşak University/1 Eylül Campus/Uşak Q. petraea subsp. iberica Quercus Samsun: 2–3 km on the Ladik road after Havza Q. infectoria subsp. infectoria Quercus Sakarya:Bilecik road to Taraklı from Geyve Q. infectoria subsp. boissieri Quercus Between Dikili-Candarlı/İzmir Q. pubescens Quercus Bayat/Afyon Q. robur Quercus Uşak University/1 Eylul Campus/Uşak Q. vulcanica Quercus Sultan Mountain/Afyonkarahisar Q. hartwissiana Quercus Between Bursa-Yalova/Güney village Q. frainetto Quercus Between Bursa-Yalova/Güney village Q. macranthera subsp. syspirensis Quercus Between Abant-Mudurnu/Bolu Q. virgiliana Quercus Abant lake/Bolu Table 1. Species, sections and localities of studied species. 22 Cytogenetics - Past, Present and Further Perspectives Q. ilex, Q. coccifera, Q. aucheri, Q. trojana, Q. cerris and Q. ithaburensis subsp. macrolepis) were germinated in the refrigerator at 4°C [29–31]. It can be stated that the method giving the best results for the germination of acorns was in the refrigerator at 4°C. As a first treatment, germinated roots in the lengths of 2–10